The New York Times reports that the strain blamed for the salmonella outbreak shows up in a Mexican-grown pepper found in a Texas distribution plant. Officials warn against eating fresh jalapeños. Bina Venkataraman writes,

Federal food officials have matched a bacterial strain found on fresh jalapeños in a Texas distribution plant with the strain responsible for what has become the nation’s largest food-borne outbreak in the past decade.

The strain found on the jalapeños, Salmonella Saintpaul, was a genetic match to the strain found in lab tests of many of the 1,251 people who have become sick from salmonella poisoning over the past three months.

It was the first time officials had found the strain on fresh produce. But the discovery still does not tell investigators whether the contamination occurred in Mexico, where the peppers were grown, or at the distribution center in McAllen, Tex. The contamination might have also occurred somewhere in between, Dr. David Acheson of the Food and Drug Administration said Monday in a conference call with reporters.

The agency is warning consumers not to eat fresh jalapeño peppers or foods containing them. The small-scale distribution plant, Agricola Zaragoza, initiated a recall of jalapeños, said Dr. Acheson, the associate commissioner of foods for the agency. But it is unlikely that the recall will account for all contaminated produce on the market because the McAllen distribution network was so small.

“We are still getting new cases reported, and do not believe that it has ended at this point,” he said. On Thursday, the F.D.A. lifted its six-week warning to consumers to avoid certain raw tomatoes, which had been linked to the outbreak after initial epidemiological studies. Michael Hansen, senior scientist for Consumers Union, said the agency did “the precautionary thing” by warning consumers not to eat those tomatoes.

Several other food safety experts said the lag in finding the source of the contamination reflected the government and the industry’s weak ability to track the source of problems in the nation’s food supply.

“The recent situation shows that we have deficiencies in the system,” said Michael Doyle, the director of the Center for Food Safety at the University of Georgia. “My experience with the industry is that in part, certain segments of the industry would rather not have food trace-back.”

David A. Kessler, an F.D.A. commissioner in the 1990s, said “the agency needs to put the industry on notice that it has to develop a full trace-back system by a specific date.”

He added: “There’s always going to be concern about costs to the industry. But what we’ve seen is that the cost to the industry that consumers are already bearing would make an investment in full traceability have a significant payback.”